The window shade field is one which has constantly undergone a variety of improvements. These have ranged from mechanical developments such as that shown in U.S. Pat. No. 5,133,399 to those applicable to the automatic window shade field. In the automatic window shade field, variations have existed for a number of years. This can be demonstrated by two patents representative of the variation, U.S. Pat. No. 4,856,574 and U.S. Pat. No. 5,170,108. As shown in each of these patents, there has been awareness of a variety of issues. While relating only to a manually operated window system, U.S. Pat. No. 5,133,399 shows an awareness of shade load issues. In the automatic context, U.S. Pat. No. 4,856,574 shows both electric operation and automatic control of the window shade raising and window shade lowering. In the perhaps an atypical example of developments using different disciplines, U.S. Pat. No. 5,170,108 to the present inventor shows sophisticated automatic operation through the use of microprocessor control with other features. These include the integration of circuitry, programming, and even optics to achieve the desired operations. In spite of this approach, the field however typically involves developers--as well as the developments--that have not typically integrated knowledge from diverse disciplines to achieve the desired goals. Thus, while goals have been long sought, it has not always been an easy task for those within this field to achieve those goals.
Certainly, other unrelated fields have utilized techniques which might have been applied to the automatic window shade field. One of these unrelated fields is that of torque sensing in general. By this field, it appears that those skilled in that art have utilized techniques which sense changes in an application of torque and utilized those changes for some purpose. As evidenced by U.S. Pat. No. 2,843,691 issued in 1958, the diverse field of torque sensing has existed for some time. Perhaps to some degree indicating how diverse this field was actually viewed by those in the automatic shade field it can be seen that U.S. Pat. Nos. 4,085,345 and 4,417,185 issued over a decade ago have shown torque sensing arrangements which might, in hindsight, be viewed as immediately applicable to the automatic shade field. In spite of this, however, those in the automatic shade field have not applied these techniques to their own field. In spite of the fact that those in the automatic shade field have long desired the operations now made available by the present invention, and in spite of the fact that the techniques and devices shown in these, unrelated fields have long been available, those of ordinary skill in the field of automatic shade operation had not previously realized the potential advantages and applicabilities to their own field. Even fairly recent developments in the automatic shade field, such as U.S. Pat. No. 5,793,174, have not seen the possibilities now explained.
Perhaps to some degree, the problems and issues facing those involved in the automatic shade field have led those away from looking at other arts. For instance, the field of the present invention is one in which there are extreme cost and installation constraints. Not only must the devices be installed and manufactured for low prices, they also have acquired space and consumer considerations which other, more general fields have not often faced. The automatic shade field has also faced a desire for easier installation so that top and bottom operations can be achieved without a need for trained installation technicians and has faced a desire to be able to react to obstructions and the like in the operation of the shade. Even in their operation, the automatic window shade field may have to some degree been viewed as unique in that the specific operations and needs of consumers can often be quite different from those applicable to a more general field.
Thus the automatic shade field may be viewed as having faced a long felt but unsatisfied need for inventions which achieve what the present does. Perhaps surprisingly, as the present invention demonstrates, the implementing arts have been available in other contexts. They have, however, not been applied in the manner of the present invention to the automatic shade field. Similarly, when applied to the field of general torque sensing, the present invention poses advantages which also utilize diverse techniques that have not been applied to even that more general field. Perhaps each of these exists to some degree because in the relevant field full appreciation of what the problem was may not have been fully comprehended by those of ordinary skill. While substantial attempts had been made to achieve some of the ends now achieved, those of ordinary skill had apparently not fully appreciated the nature or fully understood the problems involved. To some degree their efforts may even have taught away from the direction taken by the present inventor and thus results might be considered unexpected. It may even be true that those of ordinary skill in the art might have considered their field so focused and so unique that they would have considered other fields as so distinct as to not be thought to have been generally applicable to this specialized field. In achieving the goals desired, the present invention represents not just a gradual improvement over the prior art but rather a significant advance in several critical understandings. These range from advances to understanding the types of sensing systems desired, the specific operations capable of being addressed, and the physical designs used to achieve the overall goals of such an invention. These understandings have even gone beyond the mere exercise of ordinary skill into new realizations that have permitted the present inventor to address problems previously unaddressed.
Perhaps one of the more interesting historical facts which shows that the present invention truly represents leaps in performance and applications of techniques which should not be considered as obvious or a mere extension of prior efforts is shown in several US patents to Jean Bullat. Even though this lone inventor had crossed both the torque sensing and shade operation disciplines, he had apparently not fully realized how the capabilities of these two diverse disciplines could be joined. As mentioned earlier, U.S. Pat. No. 4,085,345 represents a general torque limiting stop device invented by Jean Bullat. Some years later, this same inventor also invented an improved drive system for roll-up shades as shown in U.S. Pat. No. 4,417,185. Surprisingly, even he did not fully appreciate that the techniques of his earlier torque limiting stop device could be utilized and applied in the automatic shade field. While the concept of torque reaction had been well shown in the earlier invention, it simply was not applied to the automatic shade field in his subsequent invention. As the present invention demonstrates, this cross utilization of techniques affords significant advantages. While the present invention shows that the use of torque can control both top and bottom operation of a shade as well as obstruction operation, prior to the conception of the present invention, the two fields were not even applied by the one inventor who had been active in both fields. Even beyond the use of torque to control operation, the present invention makes further advances in the utilization of electromagnetic radiation in a fashion for high efficiency and practical implementation. The present invention even goes beyond techniques in either of the two fields involved by that other inventor. Thus, until the present invention, it appears that there was no automatic shade end sensing operation which utilized torque as its control basis and no automatic shade operation which had the capability of reacting in this fashion to obstructions and the like. Even in the more general field of torque based sensing there had apparently been no use of electromagnetic control features as shown in the present invention.